Intake and exhaust valves are widely employed in cylinder heads of internal combustion engines. Such valves, supported for reciprocal motion within valve guides, typically include integral elongated valve stems extending away from the engine cylinder heads, the ends of the valve stems interacting with rotating overhead cams for cyclic or repeated opening and closure of the valves against the force of valve return springs during the combustion cycle. In order to permit unobstructed reciprocal movement of the valve stem in the valve guide, some mechanical clearance must exist between the valve guide and the moving stem. Valve stems reciprocate in and out of the cylinder head each within its individual valve guide. The valve stem seal assemblies are used to control of oil through a mechanical clearance path between each annular engine valve guide and its associated valve stem.
In the typical engine, a valve stem seal assembly is fitted over or atop each valve guide, wherein each valve stem seal assembly includes a retainer frictionally mounted to an associated valve guide. Each valve stem seal assembly normally includes an elastomeric seal for controlling oil between the valve stem and valve guide and a retainer mounted atop of the valve guide to hold the oil seal in place. Such a valve stem seal assembly takes advantage of an elastomeric seal between the retainer and the valve guide or a grip between the retainer and the valve guide.
Although valve stem seal elastomer body design, performance, and construction issues have seen much progress in recent years, there are current incentives to reduce manufacturing costs, particularly costs associated with retainers.
During the manufacturing process of the valve stem seal assemblies the retainers must be oriented, either manually or by a machine, before being inserted into molds that attach the sealing material thereto. This step can slow down the manufacturing. Therefore, there is a need for a cost-effective retainer design to accommodate a wide variety of valve guide geometries that is easy to manufacture and assemble.